The present invention relates to polymer-backed articles. The present invention particularly relates to polyurethane-backed articles, latex-backed articles, and to a process used in making same.
Articles having attached polyurethane foam layers are well known. For example, carpets and other substrates having attached polyurethane foam layers as backing are described in U.S. Pat. Nos.: 3,755,212; 3,821,130; 3,862,879; 4,022,941; 4,171,395; 4,278,482; 4,286,003; 4,296,159; 4,405,393; 4,483,894; 4,512,831; 4,515,646; 4,595,436; 4,611,044; 4,657,790; 4,696,849; 4,853,054; 4,853,280 and, 5,104,693. Typically a filler material is used to prepare a polyurethane formulation for carpet backing. The filler can replace some of the polymer required to prepare a polyurethane backed article, while maintaining bulk in the article. This can lower the cost of production of the article, since materials used as fillers are typically less expensive than the polymer material that is being replaced.
Cost reduction can be an incentive for increasing the volume of filler material incorporated into a polymer formulation. The amount of filler can be limited, however, by process parameters which are adversely affected by a high loading of filler. For example, the viscosity of a polyol mixture that includes a high concentration of filler can be increased such that the transport of the polyol mixture through a process line can be difficult or impossible. The difficulty can be exacerbated by contacting the polyol mixture with a polyisocyanate. Attempts to deliver the resulting reactive mixture to a carpet surface can produce line plugging. High viscosity also hinders the ability to properly place the resultant reactive mixture within a textured textile fabric. Further, high viscosity in a polyurethane-forming mixture can produce defects, such as gels, in a foam applied to a carpet substrate.
Non-reactive solvents or diluents can be useful in lowering the viscosity of highly filled polyol mixtures. Use of such diluents is known. However, use of a non-reactive diluent is not without problems. Adding a non-reactive diluent to lower the viscosity of a highly-filled polyol mixture can result in additional process steps to remove the diluent from the final product. Additional process steps or equipment can be required to capture volatile solvent emissions, recover or recycle used diluent, or otherwise dispose of used diluent. In addition, there is extra cost associated with supplying the diluent. These additional measures can add cost to a production process and defeat the purpose of a cost-saving measure.
It would be desirable in the art of preparing polyurethane-backed articles to increase the loading of filler in a polyurethane formulation without detriment to the process of preparing a polyurethane coating, or to the physical properties of a polyurethane-backed article. It would also be desirable to deliver a highly-filled polyurethane-forming composition to the surface of a carpet or textile substrate without incorporating a non-reactive diluent. Finally, it would be desirable in the art of preparing polyurethane-backed articles to use a process wherein an isocyanate can be used as a reactive diluent to deliver a polyurethane-forming mixture containing an isocyanate-reactive material to the surface of a carpet or textile substrate in a continuous process.